The present invention relates to the crystallization of sugars and to sugar crystals obtained thereby.
Sugars such as sucrose are very widely used, such as in the food and confectionery industries, and the final stage in the manufacturing process of the sugar is often crystallization from an aqueous solution with the sugar then being used in crystalline form. Crystallization of sugars is a complex process which is difficult to control so that the size and shape of the resulting sugar crystals is often unpredictable. Where crystals of a particular size and shape are required, for example in certain applications in the confectionery industry, it is difficult to produce crystals in the required form conveniently and consistently.
Sucrose generally crystallizes in anhydrous form although the formation of the hemipentahydrate (C12H22O11.2.5H2O) and the hemiheptahydrate (C12H22O11.3.5H2O) has been reported on crystallization at low temperature (xe2x88x9234xc2x0 C.) (Young and Jones, J. Phys. Colloid Chem., 53, 1334-1350, 1949). The formation of the crystalline hydrates was regarded as a problem in the storage of frozen fruits and investigations were undertaken to try to find ways of preventing their formation (Young et al. Food Research, 16, 20-29, 1951). Engelsen and Perez (Carbohydrate Res. 292, 21-38, 1996) suggested on the basis of molecular dynamics simulation (a computer modeling technique) and crystallographic investigation of a sucrose/protein complex that sucrose may exist in hydrated form in aqueous solution but these conclusions remain controversial.
Research into the effects of magnetic fields on chemical processes has been sporadic.
It was suggested in the 1930""s that application of a magnetic field could remove scale from water pipes but in the absence of a convincing rationale for the effect the technique remained controversial for many years before being confirmed experimentally some 50 years later (Donaldson, Tube International, January 1988, 39 and Grimes, Tube International, March 1988, 111). The effect of magnetic fields on precipitation and crystallization to inorganic systems such as calcium carbonate and zinc phosphate is assumed to be on nucleation and coagulation and the effect in reducing scale formation or even removing scale which has already formed appears to be a result of changes in solubility of the inorganic compound.
In the case of organic molecules, it was found that when benzophenone was crystallized in a high magnetic field, the direction of the long axis of the needles formed tended to align perpendicular to the direction of the magnetic field (Katsuki et al., Chemistry Letters 1996 607-608). With a more complex organic molecule, a considerable degree of alignment was found when fibrin was allowed to polymerize in a magnetic field and a possible effect on blood clotting in vivo was suggested (Yamagishi et al., J. Phys.Soc.Jpn., 58(7), 2280-2283, 1989). A recent report has also suggested that application of a magnetic field can influence the selectivity ratios in the nickel catalyzed hydrogenation of fats such as sesame oil and soybean oil (Jart, JAOCS, 75(4), 615-617, 1997).
Experiments have been reported in which passing sucrose solution through a magnetic field appeared to reduce the boiling point of the solution although a drop in boiling point was also noted for distilled water and tap water. The magnetic field also affected viscosity and surface tension of the sucrose solution but the various effects were not proportional to the intensity of the magnetic field (Bisheng et al., Int. Sugar Journal, 98, 73-75, 1996). There is no suggestion in either of these papers of any effect on the sucrose crystals themselves.
The present invention relates to a method by which the crystallization of sugars can be influenced so that a particular desired crystalline product can be formed conveniently and consistently.
The present invention relates to process for preparing crystalline sugar, the process comprising providing a solution comprising a solvent and sugar, exposing the solution to a magnetic field having a strength which is sufficient to impart improvements in the processing of the sugar or the properties of the resulting crystalline sugar product, and providing conditions suitable for crystallization to obtain a substantially crystalline sugar product.
The process includes the steps of providing a solution that advantageously contains less then 60% sugar and more than 40% water based on the total weight of the solution. It is preferable for the solution to be about 1% to 35% undersaturated and about 99% to 65% saturated.
The sugar is typically sucrose, glucose, fructose, trehalose, lactose, sorbitol, mannitol, erythritol, or combination thereof. In a preferred embodiment, the sugar consists essentially of sucrose or lactose. In another embodiment of the invention, the solvent is water and the crystalline sugar comprises sucrose hydrate containing more than about 1% water by weight. In yet another embodiment of the invention, the sugar consists essentially of lactose and water in a higher amount than known in the art.
Preferably, the strength of the magnetic field is sufficient to influence at least one of morphology, size, nucleation rate, crystallinity, or combination thereof of the crystalline sugar product. In a preferred embodiment, the solution is exposed to a magnetic field from at least one permanent magnet during the exposing step, which magnet provides a magnetic field strength of at least about 200 G. Alternatively, the solution is exposed to a magnetic field from at least one DC electromagnet during the exposing step, which magnet provides a magnetic field strength of at least about 30 G. In another embodiment of the invention, the process comprises using at least one pulsed magnet.
In the process according to the invention, at least a portion of the solution is preferably exposed to the magnetic field while evaporating an amount of solvent sufficient to the crystallization of the sugar. Thus, at least a portion of the solution is preferably maintained at a temperature of from about 30xc2x0 to about 70xc2x0 C. while evaporating at least a portion of the solvent.
Another embodiment of the invention relates to food and confectionery products prepared with the crystalline sugar products disclosed herein as an ingredient or coating.